Pitfalls when comparing COVID-19-related outcomes across studies-lessons learnt from the ERACODA collaboration

Marlies Noordzij; Priya Vart; Raphaël Duivenvoorden; Casper F M Franssen; Marc H Hemmelder; Kitty J Jager; Luuk B Hilbrands; Ron T Gansevoort

doi:10.1093/ckj/sfab027

Pitfalls when comparing COVID-19-related outcomes across studies-lessons learnt from the ERACODA collaboration

Clin Kidney J. 2021 Feb 2;14(Suppl 1):i14-i20. doi: 10.1093/ckj/sfab027. eCollection 2021 Mar.

Authors

Marlies Noordzij¹, Priya Vart^{1

2}, Raphaël Duivenvoorden³, Casper F M Franssen¹, Marc H Hemmelder⁴, Kitty J Jager⁵, Luuk B Hilbrands³, Ron T Gansevoort¹

Affiliations

¹ Department of Internal Medicine, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
² Department of Clinical Pharmacy & Pharmacology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
³ Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands.
⁴ Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands.
⁵ ERA-EDTA Registry, Department of Medical Informatics, Amsterdam University Medical Center, Amsterdam Public Health Research Institute, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands.

Abstract

Reported outcomes, such as incidence rates of mortality and intensive care unit admission, vary widely across epidemiological coronavirus disease 2019 (COVID-19) studies, including in the nephrology field. This variation can in part be explained by differences in patient characteristics, but also methodological aspects must be considered. In this review, we reflect on the methodological factors that contribute to the observed variation in COVID-19-related outcomes and their risk factors that are identified in the various studies. We focus on issues that arose during the design and analysis phase of the European Renal Association COVID-19 Database (ERACODA), and use examples from recently published reports on COVID-19 to illustrate these issues.

Keywords: COVID-19; epidemiology; kidney failure; mortality; outcomes; statistics.

Publication types

Review